The Clock Interaction Report in the PlanAhead tool treats the user TIG'ed paths as unconstrained. Following are some examples:
The PlanAhead version of the clock interaction report has some limitations, which are mentioned above. The Clock Interaction Report in the Vivado tool is clearer with additional cell colors and categories that make more sense. It indicates if two pairs of clocks are fully constrained, fully unconstrained, fully false path, partial false path, or MAXDELAY DATAPATHONLY.
Note: In the Vivado tool, two clocks are treated as related by default unless they are explicitly specified as asynchronous by set_clock_groups.
In the PlanAhead tool, use report_timing or Timing Analyzer (TRCE) to help to determine the constraints coverage.